Resin melting



March 27, 1951 KLEPETKQ 2,546,364

RESIN MEL'I'ING Filed July 5, 1947 2 Sheets-Sheet 2 INVENTOR ERNEST KLEPETKO Patented Mar. 27, 1951 I um TED STATES PATENT PF] CE RESIN MELTING Ernest Klepetko, Bauer, Utah, as sig nor to Com vbined Metals Reduction Company, Stockton, "Utah, a corporation of Utah :Applicationluly 3, 1947,=Serial No. '758,843

Claims. .1 This invention relates to melt n re n end the like, andis particularly directed to thepro-s :vision ofan mproved m hod and mpro nparatus for-melt n a resin and for c n u t y separatin -it from a volatil ma r e In :acopending application Serial No. 677,393,

filedJunel'Z, i946, noWBatent 2,506,300, Philip .de 13. Ka eoL ster H w n I h scribed an mn vednro ess f r fin g impu r sin conc ntrates obta n d fo le, from resin-bearing .Utah coal. The process therein s-described involves extracting the resin with a volatile solvent. andsubsequently evaporating the ,solvent'fromthe resin. Themethod and appatratus of the present invention are particularly well-adapted for melting the refined resin product thus produced, and may be used asa final step in that process for separatingthe resin from ,thesolventand concurrently recovering the resin vvas ameltedproduct hut are not limited'to this particular use.

easy thing to do on a largescalaibecause they are easily damaged by overheating, or even' by pro- ,longed heating at the temperature at which they are fluid; andth'eir. poor heat conductivity makes it difficult to, avoid overheating or prolonged heating. If the resin contains any significant amount of .a readily volatile resin solvent, such as the low-boiling volatile solvent used in the process of our aforementioned copending application SerialNo. "677,393; the difficulty involved in melting the resin is greatly increased. 'A resin product containing a small amount of a volatile solvent, which product is substantially solid atroom jtemperatur'a'up'on being heated for melting, first turns to a thick'liquor,"then as solvent evaporates changes toa molasses-like consistency, then'to a .viscous tarry state, and finally reverts to the solid .state evenbefore actual melting begins. During the period while the resin "is passing through theseliqui'd stages, the solvent vaporizes and the "evolved vaporiorms bubbles and foam throughout the'viscous'mass. The bubblesand foam greatly interfere "with transfer of heat to the material, thus impeding progress of the melt- "ing operation; an'd'they cause theresin, when it reverts tothesolidstate prior to melting, to ap- :pear in the form'oft'extremely fine particles. The resulting finely-divided 'solid resin is light :and ,flufly; anda considerable part of i-tis easily .car-

ried away by the current of v: escaping solvent vEMlOr. The part that remains behind is in a iormthatisani excellent heat insulator, through ;.yv,hif2h heat for melting can .be transmitted only with extreme slowness.

molten resin.

t is kno n th t to same tent the abo e:- de er bed d i ties m y D -over om by addin to the s l ent-wringin esin a ed so en having abei neranee bet e n th e p r ture a wh t fir s en boils n the e pera hi e a wh eh t e r in i e me s- Na u a re n d not ha e a sha p melt g t p r ure r er ng t theme ine tem r u e: e esin inth s ecifi t n, We me a m ere u 'e hi h enough for the uncontaminated resin to be in the form of an easily poured'liquid.) The purpose of the second solvent is to maintain'the res i .liqu i o m u il-it m ne' em e e ture hasbeen reachedand to rriinirnilzeioaniing. Whileit accomplishes these purposes "fairly eff- .iectively, 'its use-leads to still other difficulties that are undesirable in alarge-sczile resin-melting operation. For example, extra heat is required for volatiliaing the second solvent, and special e'quipmentis'requiredto'condense itfafter it has been volatilized, and "to "separate it "from the low boiling 'solvent originally present with "the resin. Also," it is'diiiicult'to eliminateall'oi "thesecond soivenvfrom the resin; even after-the latter has "been melted. The present invention provides an improved 'resin meiting methodthat "does" not'requiretheaddition' of a'second solvent.

'In accordance with 'the most advantageous practice of my inventionga body of melted resin is established-in' a"suitably 'heated vessel, and-the "incoming 'resinto bemelted is delivered atthe 'surfacepf'said body. The "body of meltedresin -isvigorously agitated adjacent'its upper surface and ne ar-the region where the incoming' resin-is introduced. 'The solvent "or other volatile material thus is -fiash-evaporated,-and the released resin is quickly-incorporated*into the body'oi-ai- --ready molten resin. GOHCHII'QHUY, theioo'dyo'f molten resin is: also vigorously agitated --well be- 'nea-th its upper surface, near --where r it I is I in contact with the heating -surface by which it' -is In -consequence of this agitation in the been incorporated into the body is quickly melted by: its r intimate contact with the iheated already A second relatively vq=uiescent body .of molten resin, communicating with the first agitateduand heat d bo y the eoimre erabl issa so e ab ished and maintained. Molten 'z esinis passed 'fromethe a ated bod to onie e t de an th e any residual volatile nia hat has :beenentra d i th eielten a y ih a t t on of the first body ha 13 1. premi m-tr r e ,Melted resinn a lh ,be-W-ithdrawn rectly fro-msthe quiescent 'body. Preferahly, wevejr, ,a 'thirgd body of molten resin, communicating with the second quiescent body, is maintained in a sump at an elevation well below the bottom level of the quiescent body. This third body' of molten resin in the sump may be heated to a temperature somewhat higher than is employed for actual melting, in order to facilitate pouring the resin, and the melted resin is Withdrawn from near the bottom level of the sump. Vaporized volatile material is withdrawn from over the quiescent body, and may be passed to apparatus designed to efiect its recovery, if such is desired. The third body of molten resin in the sump serves as a gas seal preventing escape of solvent vapor through the molten resin outlet.

It is possible for the incoming resin that is added to the agitated body or bodies of already molten resin to be in the form of a solution of the resin in the volatile solvent from which it is to be separated. Even such large amounts of solvent as are necessary to form a liquid solution of the resin are separated quite readily in accordance with my new method. Consequently the invention may be used as a final step in the process described in the above-mentioned copending application Serial No. 677,393 for separating the resin from the solvent and for separately recovering the resin as a melted product and the solvent for re-use in the process.

The new melting method may be carried out as a continuous process, by continuously adding fresh resin to be melted to the agitated body of molten resin, and continuously withdrawing melted resin from beneath the surface of the body in which it is melted, or from the quiescent body, or from the communicating body in the sump.

The apparatus of the invention comprises a vessel adapted to contain molten resin, having therein at least one partition dividing the vessel into .at least two chambers .(each of which may contain a body of molten resin). Agitator means are provided in the first of the chambers for agitating the body of molten resin therein. The partition is apertured below the normal melted resin level, to permit passage of melted resin from the first chamber to the second; and it is also apertured above the melted resin level to permit passage of vaporized volatile material from one chamber to the next. A sump extending downwardly from a second chamber, and communicating therewith, is preferably provided and is equipped with heating means to heat the resin that collects therein from the body of resin in the second chamber. Means are provided for withdrawing melted resin from near the bottom of the sump, and means for withdrawing vaporized volatile material from over the body in the second chamber also are provided.

tion of the melting vessel being shown in section;

' Fig. 2 is a view taken for the most part along the section line 2-2 of Fig. 1;

Fig. 3 is a view looking at the left end of the apparatus shown in Fig. 1;'

Fig. 4 is a' plan of the melting chambers of a modified form of apparatus; and

Fig. 5 is a section taken substantially along t he'line 5-5 of Fig. 4.

The apparatus shown in Figs. 1 to 3 comprises a vessel Ill supported above ground level on frame members ll. As shown in Fig. 1, the apparatus comprises three melting sections l2, l3, and i4, connected in series and to an end section l5. The chambers comprise drums, advantageously elliptical in cross section, provided with flanges I6 by which they may be bolted or otherwise detachably connected together. Partitions ll are mounted between each of the sections l2, l3, l4 and 15 so as to divide the vessel into separate chambers. End plates l8 and i9 close the ends of the vessel.

The vessel is adapted to contain molten resin to a normal level 26. The partitions ii are formed with apertures 2| below the normal resin level 29, thus providing for communication between the bodies of melted resin in the several sections of the vessel [0. The partitions ll also are formed with apertures 22 above the normal level 28 of the melted resin, so that vaporized volatile material may pass from one section of the vessel to and through the others in the series.

The first three sections l2, l3 and M of the vessel 10 serve as resin-melting chambers, and are provided with heaters 23 for heating the bodies of molten resin established and maintained therein, The heaters shown in Figs. 1 and 2 are tube-type immersion unit heaters, heating of which may be electrical or by circulation therethrough of a hot fluid. The use of heaters of this type has the advantage of providing a large heating area in contact with a relatively small volume of melted resin, thereby permitting rapid and efficient heating of the resin without having to maintain the resin in the molten condition for a very long period of time.

. Each of the melting sections 12, I3 and I4 is provided with a dome 24 through which an agitator shaft 25 extends. The outer end of each agitator shaft carries a pulley 26 by means of which it is driven, and inside the vessel it carries two agitator wheels 21 and 28. These agitator wheels may have the form of propellers, or any other form that produces vigorous agitation of. the molten resin when the shaft 25 is rotated rapidly. The upper agitator wheel 21 is mounted about at the normal surface level of the molten resin, while the lower agitator wheel 28 is mounted well below the normal resin level and near the heating surfaces of the heaters 23.

Incoming resin to be melted is brought to the vessel through a feed pipe 29, from which branch pipes 30 deliver the resin to each melting section so that it falls to the upper surface of the body of molten resin near the upper agitator wheel 21.

It is evident from the foregoing description that each of the sections l2, l3 and I4 is in itself a melting chamber unit. Since the melting capacity of the apparatus depends on the number of such chamber units employed, it is possible to increase or decrease the melting capacity of apparatus by adding or taking away one or more such chamber units to or from the series thereof that go to make up the vessel It].

The end section l5 of the vessel Ill differs from the melting chamber units described above in several respects. It is not provided with heaters,

'nor is it provided with any agitator means.

. s raining indies er -resin with his in com- '-'mi;iiiicat1on. 4

"The section re communicates "with vapor can-t chamber 31""oTgenerousdimensionsthrough sump 34 communicatin with the interior of the end section l5 extendsdcwnwardly to a "-bel'c'w' thebottom-o ssecticn. A th minersion tuhe y h provided for heatin the body '"Qf t collects n the siiihp. 'A rsiii oiitlt tyne, resin t -1$ipe 3&-ei tenditi" 3'! provides for withdrawing-melted resin from any the same as that described ab ve, except ier the arrangement for heating the molten resin --contained iii the melting sections. hike the a paratus described above, it comprises a vessel 40 divided into a plurality of sections 4 l, 42, i etc by partitions 43. The vessel is'adapted tO contain molten resin to a level "44, and communication between the bodies of resin in the severai sections "provided by apertures in the partitions 43 below the moltenzresin :level; Apertures '46 :above :the molten resin level are provided in the partitions topermit vapor- -ized volatile :material to pass irom :onesectioh to the next :in *the' series. An agitatorr shaft extending in'to :each melting section carries upper and lower agitator wheels 48 and 49, arranged substantially as described in connection with Figs; l to 3. --I n"coming resin "is delivered toeach melting-section through a'feedpipe 50 and branch .pipe's fo'l.

:Each meltingsect-ion 4 I ,"4 2, etc, of' the-apparatus shown inFigs. 4 and his .provided with :a heatin jacket 52, and also with immersion heating tubes 53, which are elosedat-their inner ends :54 and --comm unicate at their outer-ends with'the interior of the heatingjackettZ. Heating fluid (e. g, steam, 'hotwater or hot oil, or the like) is delivered by header pipes 55 to branchpipes 56 through which it is conducted hirectly-to'near the 'bottoin of the heating tubes 5's. At the same timefh-eating' 'fiuidi's alsode- -liver'e'd "through "other branch pipes 57 "directly "to 'the jacket 52 near the "bottom'of the vessel. Spent heating fiuid, aiter passing through the tubes to the jacket, or through the jacket itself, is "withdrawn through heating medium cxhau-st pipessa-connected to the j'acketat an elevation above that at "which the tubes 53 communicate "therewith.

The apparatus shown in Figsx i and 5"ope'rates Lin substantially'the same mannerasthat shown in Figs. 1 I to 3, and provides the advantages "of electrical "tube 'ty'p'e immersion heaters, but may be preferable 'in"localities where eiectrica1 power costs "are "high.

The method oithe 'invention'i's carried out .in ap aratus of the character described substantiall as follows (particular reference'is made to Figs. 1 to 3 in describing the method) a body or molten resin is "first "established in the 'vesserlflto'a depth indicatedbrtne surface hear the bottorncr-th'e sump ieveliine 2'0. maybeaccornplished hyfmeit ing resin" outside the'apparatus and introducing it'througlr the feed pipe 29' I or through the manholes 33 or it'rnaybe accomplished =byin troduc ing 1'es in,inthe'forin in whichit is to" benielted,

through the inlet pipe '29, and "heatin it in the vessel until it has melted. Onceestablishedjthe body of molten resin is preferably maintained continuously at the operating "temperature. If, for example, the resin is of the natural kau'ri type found in many Utah coals, and which have a melting temperature (1. e. are liquid enough to flow quitereadily) at about C as'atis'factory o erating temperature" range "is "from "200 *C. to 225 C'.

If operating conditions require it, the molten "resinin the vessel mayue allowed to cool and solidify without particular harm. Once it has been melted and freed from at least the'lowboiling volatilematerial, itcan be remelted, after solidifying, by means'of theheaters imbedded-in it, without great difiiculty. Substantial time may, however, be required for remelting, and

some injury may be donethe resin'by heating'it for the length of time required for remelting. For this reason it is best not to allow the resin to solidify in the melting vessel if such "canbe avoided.

With the body of resinestablished in'the vessel'at the desired "operatingtemperature, incomiing're'si'n is delivered, advantageously continuously,'through the resininlet pipe Bend the branch pipes 3 ll'to at'lea st the first resin-melting section 12, and advai'itageouslyto all such sections 52, I3 and I 4 "of the apparatus. The incoming resin'may be either in the form of solid material blown or otherwise forced throughthe pipe 2 9,

or it may be in solution'in 'the volatile low bo'iling solvent. The resin torresin-bearing solution) drops directly on to the upper surface of the body of hot'molten resin, and the solvent is for'the most 'part immediately flash-evaporated. The agitators 2! and 28"a're'rotatedrapidly enough to cause vigorous agitation of "the bodyfof molten resin. The upper agitatonziservestc breakup any" froth that tends to form and to cause immediate release "ofmost, if not all, of them- "pori'ze'd solvent. "It also stirs" the residual solid non-vo1ati1ized resin immediately into the body of molten resin, wherein it is quickl melted by direct contact with'the already'molten material. The lower agitator, by producing vigorous agitation of"them'olten resin at an'appreciable depth below the surface andfnear the heaters 23, insures effective andrapid transfer ofheat by conwith which it is present is introduced directly'on to the surface of the vigorously agitated body of molten resin,'that even-a rather dilute solution of "resin'in'such solvent may be delivered directly to "the melting chambers. Substantially complete Hash-evaporation of 'ev'en'such a relativelylarge "amount of solvent 'is "effected, and substantially complete recovery of the resin in the moltenxbo'dy of resin is'achieved. Hencethe "method maybe usedas thefinal ste'p'ina resin recovery or refining "process, involvlng'dissclving quiescent state.

the resin in a low-boiling solvent (as described in the above-mentioned copending application Serial No. 677,393), to effect separation and separate recovery of both the resin and the solvent.

The volatile material vaporized in the melting units l2, l3 and it passes through the upper apertures 22 in the partitions I? to the vapor outlet chamber 3|, and thence through the pipes 32 to the condensers in which the volatile material is recovered, or to waste if recovery is not worthwhile.

As resin is introduced into and melts in the melting chambers l2, l3 and I4, molten resin passes through the apertures 21 in the partitions ll below the molten resin level 28 to the unheated end section 55. As there are no agitators in this section, and as the body of resin therein is quite effectively isolated by the partitions i? from the eifect of the agitators in the melting sections [2, l3 and Hi of the vessel, the body of molten resin in the end section i is substantially quiescent. Here any solvent vapor that has been stirred by the agitators into the body of molten resin, or that for some other reason has not escaped in the melting chambers, is enabled to do so, and to pass into the vapor outlet chamber 3|. I a

The partition ii that is between the end section [5 and the adjoinin melting section i i is, of course, the most important of the series of partitions, because it separates a vigorously agitated melting chamber from the chamber in which the resin is held in a substantially tranquil or Hence the apertures 2| and 22 therein should be respectively well below and well above the molten resin level 29, and no apertures should be present very near this level. The other partitions I1 between adjoining melting sections may be omitted from the apparatus if desired, although they serve the useful purpose of dividing the molten resin in the melting sections of the vessel into a series of relatively small bodies that are particularly easy to agitate and heat. It is sometimes desirable to heat the body of resin in each resin-melting chamber to a somewhat higher temperature than prevails in the preceding chamber in the series, so that a temperature gradient increasing from the first chamber i2 to the last chamber 14 in the series is established in the vessel. This is particularly desirable whenever the resin contains a relatively high-boiling volatile contaminant, because it facilitates rapid and complete elimination of such contaminant from the resin. The presence of partitions ll between each melting chamber !2, i3, and M facilitates establishing such a temperature gradient.

The end section it, in which the body of molten resin is substantially quiescent, is preferably unheated except to the extent that the resin therein is in communication with heated sections of the vessel, as I have found that this leads to more effective escape of residual solvent vapor.

The only outlet for molten resin'entering the end sectioni5 is into the sump 3 3, and it is from this sump that the resin is withdrawn for casting into drums for shipping, or into other containers. Since the resin is withdrawn from near the bottom of the sum and the gaseous solvent rises, there is little opportunity for any solvent vapor to fiow out through the pipe 36 with the molten resin. The resin in the sump may be heated by the heater 35 to a higher temperature than elsewhere in the apparatus for ease in withdrawing and casting it.

Since the bottom of the sump is the lowest point in the system, it is convenient for use in draining the molten resin from the apparatus when such is desired for cleaning or other purposes. Much of the molten resin can be drained by syphon action of the discharge ipe 35, and complete drainage may be effected by removing the sump bottom plate, or through a drain cock provided in the sump bottom. The pipe 36, which extends almost to the bottom of the sump, provides a gas seal preventing escape of vapors of volatile material through the pipe when only a small amount of molten resin or resin solution has collected in the bottom of the sump, when the apparatus is refilled.

The new melting method results in virtually complete elimination of low-boiling volatile material from the resin, even when the amount of such volatilematerial is suilicient in amount to form a, liquid solution of the resin. Hence the melted resin product is substantially pure. Substantially complete elimination of low-boiling resin solvent is important, as the presence in the resin product of any foreign material that lowers its melting point lessens its commercial value.

The new melting method may be carried out continuously, thus making it well adapted for large scale'melting operations, and in the final stage of a continuous resin-refining process.

The new apparatus enables the method of the invention to be carried out with but a small volume of molten resin in relation to the amount of resin that can be melted. This it accomplishes by providing a large total area of heating surface in the melting sections in relation to the volume of molten resin therein. Consequently the rate at which the resin passes through the apparatus is high, and the resin is not heated at its melting point long enough to be affected deleteriously. The vigorous agitation provided by the new apparatus, in conjunction with the large amount of heating area relative to the volume of resin in the several bodies thereof, insures rapid heating of the resin to its melting temperature without permitting any local overheating, with consequent danger of damage to the resin.

It is evident from the foregoing that the new method and the new apparatus are effective for producing, efficiently and economically, a melted resin product of high quality.

I claim:

1. The method of reducing to the molten con-- dition a resin in solution in a solvent therefor with removal of the solvent from the resin, the evaporation of the resin solution being characterized by passing through a stage wherein volatilized solvent produces a voluminous froth composed of bubbles of viscous resin solution, which comprises establishing and maintaining a molten body of the resin, applying heat to said body of molten resin, agitating the body of molten resin sufficiently to facilitate distribution therethrough of said applied heat, introducing the resin solution to be evaporated onto the surface of said body at a rate such as to maintain said mass of froth, vigorously agitating the resulting froth adjacent the surface of said body, whereby separation of the solvent and resin is effected by volatilization of the solvent and melting of the re sidual resin, and withdrawing molten resin from said body thereof.

2. The method of reducing to the molten'condition a resin in solution in a solvent therefor guests.

removal. of-itheisolvent from -the resin, the,

cvaporation'of the resin solution being. characterized bypassing-through a stage wherein volae. tilized. solvent produces avoluminous froth composedof bubbles of viscous resin-solution, which v comprises establishing and maintaininga molten body of the resin, applying heat to the interior; of said body of molten resin, agitating the body of molten resin sufficiently to facilitate distribution therethrough of said applied heat, introduce ing the resin solution to be evaporated onto the.

surfaceof said bodyat a rate such as to main tainsaid mass of froth, vigorously agitatingthe resulting-froth adjacent thesurface of said body,-

whereby separationiof the solvent and resin; is cffectedby,volatilization f thesolvent and melt ingof the residual resin, and withdrawing fmoltenresinfrom saidbody thereof.

tilized: solvent produces a -voluminous-.froth composed of bubbles of viscous resin solution, which: comprises establishing and maintaining a molten body of-the resin, applying heat to the interior-of said ;bodyof molten resin, agitatingthegbody of molten resin sufiicientlyito facilitate distribution therethrough of said applied heat, introducing the" resinsolution to be evaporated ontothe'surface ofsaid body at a ratesuch :as to maintain said: mass ,Of froth; vigorously agitating the. resulting;- fwroth -adjacent: thesurfaceof said body, whereby; separationof the solvent :and. resin iseffected by; volatilization ofithesolvent. andmelting of the residual resin, continuously transferring the:

molten resin from saidjagitated body to a relatively quiescent zone wherein any volatilized solvent physically entrapped therein may escape and thereby form a body of the resin in molten condition substantially free from said solvent, and withdrawing molten resin from said quiescent body thereof. 7

4. The method of reducing to the molten 0011+ dition a resin in solution in a solvent therefor with removal of the solvent from the resin, the evaporation of the resin solution being char: acterized by passing through a stage wherein volatilized solvent produces a voluminous; froth composed of bubbles of viscous resin solution, which comprises establishing and maintaining a molten bodv of the resin, applying heat :totsaid body of molten resin, agitatingthe body-of molten resin sufliciently to facilitate distribution therethrough of said applied heat, introducing the resin solution to be evaporated onto the sur face -of saidbody at a rate such as to maintain said :massof". froth, vigorously agitating the: ree sulting' froth, adjacent the, surface" of said body, whereby separation of the solvent and resin is effected by volatilization of the solvent and melting of the residual resin, continuously transferring the molten resin from said heated body thereof to a relatively quiescent zone wherein the molten resin is heated only indirectly by its communication with said heated body of resin, whereby any volatilized solvent physically entrapped therein may escape, and withdrawing molten resin from said quiescent body thereof.

5. The method of reducing to the molten condition a resin in solution in a solvent therefor with removal of the solvent from the resin, the evaporation of the resin solution being characterized by passing through a stage wherein volatili edtsolvent produ es. a vo uminou ot composed 1 of, bubbles 3 of viscous resin solution, which.v ompr s s. establ shin and ain a n ng, first, second and third molten bodies of the resin, applying .heat to the firstand third of. said bodies of. mo t re the e on o f moltenresin being heated substantially only by its communication with the other heated bodies thereof, saidthird body extending to .a,bottom level below the bottom level of thefirst and sec- 0nd bodies, agitating the V first body of 7 molten resin sufficiently to facilitate distribution therethrou h, id. app ed. h t. ntr uci o. e ins mti n o be or d. nto tho r aco of aid. fir t b d arote. uch. s; o ma ntain said. mass of froth, vigorously agitating the re- 1ting..f o h' d a ent o urface aid body, whereby separation ofthe, solvent and; resin is effected byvolatilization of the solvent andmelt ing of the residual resin; and,v withdrawing mole ten resin, from near the bottom level ofsaid third body,

Ina proce sf he oo v rv a efin d. osin p od t. nvo in t ctin the, esin with a solvent having.a, boiling. point substan: tially below the melting ,temperatureof the resin,.the step of concurrently evaporatipgthesol: ventfrom the resin solution and recovering thje resin in a. meltedsubstantially solvent-freew dition, the evaporation of" the resin solution being characterized byv passing througha. stage he ein volat li ods l ont p du es avo um a nous ro h; composed i uloblesof vi o us os lutio wh ch. omprises stabl sh n nd."

ainta n n a. mo t n... body of, he, os pplyins. hea ot aid'. y. o mo t n. re in, agitating.

the body of jmolten resin sufficiently to fa ci1i= tate distribution, therethrough of, said applied,

heat, nt ducin o e in o u on e ova.-

porated onto the surface of said body at; a rate such as. to maintainsaid massof froth, vigorously agitating the resultingfroth adjacent the;

surface f a d body..w r by e arationof. the

solvent and resin is effected by volatilization of" the solvent; and,melting of; the residual resin,

and withdr w ng. mol en. resin rom ai bod thereof;

7. Apparatus for reducing to the molten condition a resin in, solution in a solvent therefor with removal of the solvent fromthe resin, the

vaporatio of he r n. o on ei har.- ct z d by pa sin hr h. a. st e where n o atilizodso v n produces 011 inous froth. mposed. o u lesf. i ou sin. tion. hich com ises a essel. ad pt d. o ont ina. mass; he o n. m oondition, at lea t,

one ubst ntially r al y is o ed apertured Par io po o od t inthe ve se an g dr nc, ai v ssel nto ea t s r but.

mm nicat n mol n... osinr n ain e m.- partments, an agitator disposed within one of the compartments and adapted to effect vigor- 8. Apparatus for reducing to the molten condition a resin in solution in a solvent therefor with separation of the solvent from the resin, the evapora ion of the resin solution being characterized by passing through a stage wherein volatilized solvent produces a voluminous froth composed of bubbles of viscous resin solution, which comprises a vessel adapted to contain a mass of the resin in molten condition, at least one substantially vertically disposed apertured partition positioned within the vessel and dividing said vessel into at least two separate but com.- municating molten resin-containing compartments, an agitator disposed within one of the compartments and adapted to efiect vigorous agitation of a body of molten resin therein, heating means disposed Within the vessel in such manner as to apply heat to the interior of said agitated body of molten resin, supply means for introducing the resin solution onto the surface of the agitated body of molten resin, a second agitator disposed above the first-mentioned agitator and adapted to effect vigorous agitation of froth formed adjacent the surface of the agitated body of molten resin by volatilization of solvent contained in said resin solution, the other compartment being free of agitating means, and discharge means for withdrawing substantially solvent-free molten resin from said other compartment.

9. Apparatus for reducing to the molten condition a resin in solution in a solvent therefor with separation of the solvent from the resin, the evaporation of the resin solution being characterized by passing through a stage wherein volatilized solvent produces a voluminous froth composed of bubbles of viscose resin solution, which comprises a vessel adapted to contain a mass of the resin in molten condition, at least one substantially vertically disposed apertured partition positioned within the vessel and dividing said vessel into at least two separate but communicating molten resin-containing compartments, an agitator disposed within one of said compartments and adapted to effect vigorous agitation of a body of molten resin therein, heating means for said agitated body of molten resin, suppl means for introducing the resin solution onto the surface of the agitated body of molten resin, an agitator disposed within the vessel and so positioned as to effect vigorous agitation of froth formed adjacent the surface of the body of molten resin by volatilization of solvent contained in said resin solution, the other compar ment being free of agitating means, a sump extending downwardly to a level well below the bottom of the vessel and communicating with said other compartment, heating means for molten resin within the sump, and discharge means for Withdrawing substantially solvent-free molten resin from near the bottom of said sump.

10. Apparatus for reducing to the molten condition a resin in solution in a solvent therefor with removal of the solvent from the resin, the evaporation of the resin solution being characterized by passing through a stage wherein volatilized solvent produces a voluminous froth composed of bubbles of viscous resin solution, which comprises a vessel adapted to contain a mass of the resin in molten condition, said vessel being composed of an end chamber provided with means for withdrawing molten resin and volatilized solvent and a plurality of resin melting chambers connected together in series and to said end chamber, each of said series of melting chambers comprising a unit chamber detachably joined with other like units whereby the resin melting capacity of the apparatus may be increased or decreased by adding or removing one or more such chamber unit to or from the series thereof, a substantiall vertically disposed apertured partition positioned within the vessel between the end chamber and the adjacent melting chamber and dividing said chambers into two separate but communicating molten resin-containing compartments, heating means for said melting chamber, supply means for introducing the resin solution onto the surface of the body of molten resin in the melting chamber, an agitator disposed within the melting chamber and so positioned as to effect vigorous agitation of froth formed adjacent the surface of the body of molten resin by volatilization of solvent contained in said resin solution, the end chamber being free of agitating means, and discharge means for withdrawing substantially solvent-free molten resin from said end chamber.

ERNEST KLEPETKO.

REFERENCES CITED The following references are of record in the file of this patent:

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1. THE METHOD OF REDUCING TO THE MOLTEN CONDITION A RESIN IN SOLUTION IN A SOLVENT THEREFOR WITH REMOVAL OF THE SOLVENT FROM THE RESIN, THE EVAPORATION OF THE RESIN SOLUTION BEING CHARACTERIZED BY PASSING THROUGH A STAGE WHEREIN VOLATILIZED SOLVENT PRODUCES A VOLUMINOUS FROTH COMPOSED OF BUBBLES OF VISCOUS RESIN SOLUTION , WHICH COMPRISES ESTABLISHING AND MAINTAINING A MOLTEN BODY OF THE RESIN, APPLYING HEAT TO SAID BODY OF MOLTEN RESIN, AGITATING THE BODY OF MOLTEN RESIN SUFFICIENTLY TO FACILITATE DISTRIBUTION THERETHROUGH OF SAID APPLIED HEAT, INTRODUCING THE RESIN SOLUTION TO BE EVAPORATED ONTO THE SURFACE OF SAID BODY AT A RATE SUCH AS TO MAINTAIN SAID MASS OF FROTH, VIGOROUSLY AGITATING THE RESULTING FROTH ADJACENT THE SURFACE OF SAID BODY, WHEREBY SEPARATION OF THE SOLVENT AND RESIN IS EFFECTED BY VOLATILIZATION OF THE SOLVENT AND MELTING OF THE RESIDUAL RESIN, AND WITHDRAWING MOLTEN RESIN FROM SAID BODY THEREOF. 